Parachutes generally include a harness adapted to surround the upper torso of a parachutist or adapted to surround cargo, a canopy (usually umbrella or wing shaped) for creating air resistance, and suspension lines connecting the canopy to the harness. A parachute also includes a bag or container into which the canopy can be folded and from which the canopy may be selectively discharged by a pull cord. When the canopy is folded within the bag or container, the suspension lines are folded in a zig-zag manner. In order to releasably secure the looped ends of the suspension lines to the container, two opposing series of looped stowage holders are provided on the container, and a rubberband or bungie cord is looped through a corresponding one of the stowage holders and then around the looped ends of the suspension lines.
When the canopy is selectively discharged from the container, then the suspension lines will be withdrawn from their zig-zag, folded condition by the tension exerted on the suspension lines due to the air resistance experienced by the canopy. When the suspension lines are unfolded, then the rubberbands or bungie cords must stretch and permit the looped ends of the suspension lines to be released. During this unfolding process, the bag or container tends to flip-flop due to the suspension lines tugging alternately at the rubberbands or bungie cords attached to a stowage holder in one series, and then the other series.
The foregoing description of parachute construction and operation is readily known and understood by parachutists and is revealed in such publications as U.S. Pat. Nos. 2,366,764; 2,978,212; 3,940,095; and 4,034,940.
The use of rubberbands to releasably maintain the parachute suspension lines in a zig-zag, folded condition suffers from a few drawbacks. First, since the rubberbands have squared or cornered edges, the rubberbands will tend to snap or flip away or off from the looped suspension line ends when the suspension lines are subjected to the tugging force of the canopy. Also, because of the tremendous forces associated with such tugging, the rubberbands tend to break relatively often, thereby requiring frequent replacement. Both of these features--the snapping or flipping of the rubberband away or off from the looped ends of the suspension lines and the breakage of the rubberbands--tends to cause the bag or container to flip-flop radically as the suspension lines are unfolded. Such flip-flopping can result in the suspension lines becoming tangled or twisted, which can cause parachute malfunction, and also can result in an erratic flight, which can cause nearby parachutists or their parachutes to bump into each other.
The use of bungie cords instead of rubberbands also suffers from several drawbacks. Bungie cords are fashioned of solid elastic or rubber, and therefore tend not to stretch very much. Although the bungie cords do not have any square or cornered edges, they still do not roll or twist very well. Also, the bungie cords tend not to break, even though it is desireable that the bungie cords break when the suspension lines are severely snagged during the unfolding process.